A high-throughput cheese manufacturing model for effective cheese starter culture screening

Microplate and stirring device used for the manufacturing of 96 individual microcheeses.

Acidification profiles in border wells and nonborder wells show no significant positional effects. Gray circles show pH values measured in various nonborder wells (positions B2 to G11; n=15); black squares show pH values in border wells C1, F1, H2, H6, and H12. Error bars show standard deviation.

Acidification of Gouda (panel A) and Cheddar (panel B) type microcheese during the first 24h illustrate the reproducibility between individually manufactured microcheeses. Diamonds and squares represent microcheeses made on different days. Error bars show standard deviation (for each data point, n=10).

Comparative analysis of cheese microstructure: confocal laser scanning microscopy images of a 35-d-old Gouda-type microcheese (panel A) and an industrially manufactured 35-d-old Gouda-type cheese (panel B) show a highly similar coalescence pattern. The cheese was stained with Nile Blue to visualize the lipid inclusions (white) in the cheese matrix. Each panel shows 2 images from different sections of the preparations.

Multidimensional (Dim=dimension) scaling plot of GC-MS peak areas (Table 2) of volatile compounds measured in microcheese after 42 d of cheese ripening. The analysis is based on supervised random forest, and the results allow distinguishing of 4 different types of microcheese and industrially manufactured cheese. Gouda without adjunct (FR18, □), Gouda with adjunct (FR18-APS,■) Cheddar without adjunct (RA21, ▵), Cheddar with adjunct (RA21-FLAV54, ▴), and industrially manufactured Gouda (Jonge Beemster, *).

Proteolysis in microcheese and industrially manufactured cheese as determined by reverse phase-HPLC. The levels of various casein fractions and their degradation products are shown. Industrially manufactured cheeses (white bars) are compared with microcheeses (gray bars). The 3 panels represent 14, 41, and 124 d of ripening time from top to bottom, respectively. Missing bars indicate that those peptides were not detectable. The identified peptides are indicated on the x-axis and the peak areas are indicated on the y-axis. Error bars show standard deviation (n=4). Fragments a_S1-Ia, a_S1-Ib, and a_S1-Ic are degradation products of α_S1-casein; fragment b-cas-I is a degradation product of β-casein. With the exception of peptide α_S1-1b, the protein degradation in the 2 types of cheese is very similar.

Quantification of volatile flavor compounds as measured in a conventionally produced cheese (white bars) and microcheese (gray bars) after 41 d of ripening. Error bars show standard deviation (n=5). The identified compounds are given on the x-axis and peak areas are given on the y-axis. Overall, the data obtained from microcheese and industrial cheese show good correlation.

Gouda microcheese production with (engineered) adjuncts, high in 3-methylbutanal production, and the isogenic control strains. Peak areas of 3-methylbutanal concentrations as measured after 41 d of ripening. The indicated strains are Lactococcus lactis B1157 (n=4); a derivative with an inactivated branched-chain α-keto acid decaboxylase (bckad) gene B2083 (n=5); a bckad overexpression strain NZ9000 pNZ7500 (n=5); and a corresponding control strain MG1363 (n=5). Whiskers show the total range of measured values. The boxes show the median and the 25th and 75th percentiles.